The emerging social media brand community provides a good platform for marketers to promote brand to their members. Marketers are devoting time and effort in building their social media fan page; however, the elusive question of whether their social media fans exhibit any behavioural loyalty in terms of actual purchase behaviour remains unanswered. Based on the characteristics of social media, we treat social media fan membership as the objective indicator of attitudinal loyalty. This study validates the positive relationship between social media attitudinal loyalty and behavioural loyalty by proposing three models on purchase expenditure, quantity and frequency. We used treatment effects model to account for selection bias problem. Our data for model estimation consist of customers? transaction data and their fan membership to the brand on Facebook. This study shows fans of the brand have higher behavioural loyalty than non-fans in terms of all the three purchase behaviour aspects.